The present invention relates to a metal member welding technique and, more particularly, to a weld strength guaranteeing technique for a welded metal plate.
The present invention also relates to a strength guarantee determination technique in a casing structure for an image forming apparatus.
As a technique of overlaying base materials and welding them, those as disclosed in Japanese Patent Laid-Open No. 9-47873 are known.
Welding techniques for a casing structure for an image forming apparatus such as a copying machine or laser beam printer are disclosed in Japanese Patent Laid-Open Nos. 11-135956 and 11-346065.
Regarding a device casing structure for an industrial product such as an office machine, e.g., an image forming apparatus, or an industrial machine, sometimes the structure has a complicated shape or an odd shape other than a square or rectangular shape.
In such a casing structure, sometimes the structure is formed by welding a plurality of metal plates, and the mechanical strength of the structure is therefore guaranteed.
In strength guarantee for a welded portion of metal plates, the welding conditions are set considering various factors such as the thicknesses of the metal plates to be welded, welding means, the necessary design strength of a casing structure to be welded. The casing welded on the basis of the preset welding conditions is subjected to a strength test to obtain optimal conditions. Strength guarantee is performed with the optimal conditions. Due to factors such as variations in size of the metal plates and a change in conditions of the welding means, sometimes the strength of the welded casing is not sufficiently guaranteed for.
At the manufacturing site of the casing structure, the welding conditions are altered to correspond to a change in various types of manufacturing states, e.g., alteration of the welding conditions due to a change in the type of the metal members to be welded or in thicknesses of the members. Each time the welding conditions are altered, a test must be performed to guarantee the strength of the welded casing. When the welding conditions are altered often, checking the strength guarantee adversely affects productivity.
The present invention has been made in view of the above problem, and has as its object to facilitate determination of the weld strength of welded target bonding members when a plurality of metal members are welded.
In order to solve the above problem and to achieve the above object, a weld strength determination method according to the present invention is characterized by the following process.
More specifically, when a plurality of metal members are welded, a weld strength of welded target members is determined on the basis of the state of a lower bead.
According to the first aspect of the present invention, a casing structure for an image forming apparatus is characterized by the following arrangement.
More specifically, according to the present invention, there is provided a casing structure for an image forming apparatus, which has a casing formed by welding a plurality of metal plates, wherein a length of a lower bead of a welded portion of the welded casing structure is set to not less than a predetermined length, so a strength of the casing structure is guaranteed for.
According to the second aspect of the present invention, a casing structure for an image forming apparatus is characterized by the following arrangement.
More specifically, the casing structure comprises a frame member for placing an original unit and an optical unit thereon, and a plurality of side plate members, a bottom plate member, and a front plate member to be fixed to the frame member, wherein the frame member and the plurality of side plate members, the bottom plate member, and the front plate member are partially overlaid and welded with a laser to form a three-dimensional structure.
A weld strength determination method in an image forming apparatus according to the present invention is characterized by the following process.
More specifically, there is provided a weld strength determination method in a casing for an image forming apparatus which comprises a frame member for placing an original unit and an optical unit thereon, and a plurality of side plate members, a bottom plate member, and a front plate member to be fixed to the frame member, and in which the frame member and the plurality of side plate members, the bottom plate member, and the front plate member are partially overlaid and welded with a laser, characterized in that a weld strength is determined on the basis of a size of a weldline appearing on a lower surface of a portion which is welded with the laser.
A casing structure according to the present invention is characterized by the following arrangement.
More specifically, there is provided a casing structure in which a casing is formed by three-dimensionally combining and coupling a plurality of metal members and which comprises a board member and a plurality of plate members to be coupled to the board member, wherein the board member and the plurality of plate members are partially overlaid and welded with a laser, and a ratio of a length of an upper bead to a length of a lower bead of a portion which is welded with the laser is set to not less than a predetermined value.
Other objects, features and advantages of the present invention besides those discussed above shall be apparent to those skilled in the art from the description of a preferred embodiment of the invention which follows. In the description, reference is made to accompanying drawings, which form a part thereof, and which illustrate an example of the invention. Such example, however, is not exhaustive of the various embodiments of the invention, and therefore reference is made to the claims which follow the description for determining the scope of the invention.